1. Field of the Invention
The present invention relates to an apparatus for increasing the effective diameter of an expansible reel. The present invention more particularly relates to an apparatus for increasing the effective diameter of an expansible payoff reel so that metal coils of varying internal diameters may be retained securely on the reel during payoff of the coiled metal.
2. Description of the Invention Background
During manufacture and treatment, steel strip may be coiled on reels of varying diameters to provide steel coils with varying inside diameters. The coiled steel strip subsequently may be subjected to various finishing treatments and processes and the coils must be unwound into processing equipment from a payoff reel. To securely hold the steel coil during payoff into the processing equipment, the payoff reel typically is capable of expanding to increase its outer diameter. The coil initially is disposed on the payoff reel while the reel is in an unexpended state and has a relatively small outer diameter. The reel's unexpended state is referred to herein as its "collapsed" configuration. The reel is then mechanically expanded to assume what is referred to herein as an "engaged" configuration in which the diameter of the reel is enlarged to securely grip the coil's inside diameter.
Because coils may have different inside diameters, payoff reels often must be equipped with some means to increase the effective diameter of the payoff reel so that it will securely grip the coil's inside diameter as the payoff reel expands. One method for increasing payoff reel diameter is to insert lengths of 2".times.4" or 4".times.4" wood between the coil's inside diameter and the payoff reel before expanding the reel. This method is unsatisfactory because the coils may slip on the payoff reel and any wood splinters may damage the internal mechanism of the reel.
An alternative method to increase the outside diameter of an expansible payoff reel is to removably attach a series of buildup plates, typically composed of steel or nylon, to outer surfaces of those segments of the payoff reel that contact the coil's inner diameter. Each steel buildup plate may weigh in excess of 100 pounds and is difficult to handle and install. Installation of steel buildup plates normally may require 30-45 minutes and removal another 30-45 minutes, during which time the processing equipment will be unavailable for use. To facilitate installation of buildup plates, the plates may first be attached to the inner diameter of two steel rings in the orientation in which the plates would be when connected to the payoff reel. The assembly of plates connected to the rings is then disposed over the payoff reel, the buildup plates are bolted in position onto the reel and then the steel rings are removed from the buildup plates. Positioning the assembly of plates and rings over the reel is difficult and a coil buggy must be used because the assembly is quite heavy. Also, no net time savings is achieved using the steel rings because additional operations are required to remove the rings from the buildup plates during their installation on the reel and to replace the steel rings over the buildup plates before removing the plates from the reel.
Accordingly, a need exists for an improved apparatus to increase the diameter of an expansible payoff reel. The improved design must allow the reel to completely expand and securely grip the inside diameter of a coil. The improved design should also be quickly installed and removed, and should remain in place on the payoff reel when the coil has completely payed off of the reel.